“I will now make it my upmost priority to bring our party and our country together because that is the only way we will overcome the challenges we face and build a better, more prosperous future for our children and our grandchildren,” he said. “I will work day in, day out to deliver for the British people.”

Sunak will officially become prime minister after he meets with King Charles, the head of state, and is asked to form a government. That is likely to happen on Tuesday.

The pound briefly topped US$1.14 on Monday as it became apparent Sunak was likely the next prime minister.

Sunak will enter office just over four months after quitting as chancellor, a move that heaped pressure on Johnson to resign.

Sunak will face several challenges as the new prime minister, uniting the Tories and navigating a generation-defining economic crisis that threatens to force millions of ordinary Britons into poverty.

Truss had sought to tackle the crisis, which is being driven by high inflation and sharp rises in energy prices, by spending £60 billion (US$68 billion) to help the British public navigate those surging costs, while pushing through £45 billion (US$51 billion) in tax cuts.

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UK Prime Minister Liz Truss resigns, ending the shortest leadership term in modern British history

UK Prime Minister Liz Truss resigns, ending the shortest leadership term in modern British history

However, questions about how she would pay for the support package unnerved financial markets, sending the pound to its lowest level against the US dollar in 50 years in late September and pushing mortgage rates and government borrowing costs sharply higher.

As a result, the Bank of England stepped in and bought government bonds to stabilise financial markets that threatened to upend major British pension funds.

Truss was forced to roll back much of her tax-cutting plans last week, but ultimately lost the confidence of Conservatives following a chaotic night in Parliament last Wednesday that saw Tory MPs allegedly manhandling their colleagues during a vote and further amplified the apparent disarray in her government.

On Friday, credit rating agency Moody’s Investors Service changed its outlook for Britain’s domestic and foreign-currency long-term credit ratings to negative from stable.

“The evolution of policymaking, and the UK government’s ability to engender confidence in its commitment to fiscal prudence, will be a material consideration for Moody’s in resolving the negative outlook,” the credit rating agency said.

Inflation eclipsed 10.1 per cent in September, putting further pressure on consumers and small businesses.

Sunak, 42, is the first person of Indian descent to become Britain’s prime minister. He was born in Southampton in 1980, where his father worked as a doctor and his mother ran a pharmacy.

He met his wife – the daughter of Indian billionaire Narayana Murthy – while studying for his master’s of business administration degree at Stanford University. He worked at Goldman Sachs and two hedge funds before being elected to Parliament in 2015, and served as chancellor from 2020 until July of this year.

In addition to tackling an economic crisis, Sunak will face a challenging geopolitical landscape following Russia’s invasion of Ukraine and a more fraught relationship with Beijing amid growing distrust of China in Britain.

As a candidate, he threatened to ban all 30 Confucius Institutes in Britain. The language and cultural centres have been controversial, with critics accusing them of acting as a propaganda arm for Beijing and stifling on-campus speech about sensitive subjects, such as Taiwan or Xinjiang.

Sunak also will have to unify a Conservative Party that split into warring factions this summer with Johnson, who remains popular among Tory members, waiting in the wings.

Johnson claimed 102 MPs had been willing to support him, but the BBC’s running tally was less than that on Sunday. He needed 100 to qualify for Monday’s ballot.

44 days as PM nets Truss a US$129,000 yearly stipend … for life

Johnson, who continues to serve as an MP, is facing an inquiry by the House of Commons privileges committee about whether he misled Parliament by denying lockdown rules were broken at Downing Street during the coronavirus pandemic.

“I am afraid the best thing is that I do not allow my nomination to go forward and commit my support to whoever succeeds,” Johnson said in a statement late on Sunday. “I believe I have much to offer but I am afraid that this is simply not the right time.”

At the same time, calls are growing among opposition parties and some Tories for a general election. The next one is set for January 2025, but the disarray among Conservatives recently is piling pressure for an earlier election.